Power Scaling vs. Power Brake

[Mats A]

What is the big difference in tone when using the Power scaling compared to a Marshall Power Brake that is a reactive load? Except from the obvious of course that with the PS you don´t have to carrie around an extra quite heavy box. To me the tone that Chris got playing the YJM at NAMM was not too different from the tone i get on my plexi reissue with the Power Brake.

[KevinOConnor]

Hi Guys

How attenuators operate, the nature of sound, how Power Scaling works and many other things are explained in great detail in TUT4 (The Ultimate Tone vol.4).

With Power Scaling, only as much power as you need is generated and the amp is solidly connected with the speaker. The amp-speaker interaction is not disturbed.

Attenuators decouple the amp from the speaker more and more as greater attenuation is desired. This eliminates the interaction between them and alters the sound.

The Power Brake uses an autotransformer - tapped single-winding transformer - to achieve attenuation. A speaker load emulation circuit is wired in parallel with this, so the amp sees a reactive load of "some kind". As greater attenuation is dialed in, the autotransformer turns ratio between the selected tap and the full winding effectively increases damping of the speaker, changing the sound. You may like this change.

For small amounts of attenuation, load boxes of any type will work okay. Beyond 8dB attenuation, the sound changes. How much of this you notice or care about is your own paradigm - and you are correct in your opinion. If an attenuator "works" for you, just go with it.

Have fun
Kevin O'Connor

[thunderkyss]

Hi Guys

How attenuators operate, the nature of sound, how Power Scaling works and many other things are explained in great detail in TUT4 (The Ultimate Tone vol.4).

Kevin O'Connor

Kevin, I appreciate all the info you've brought to the forum. I do agree with the "if attenuators work for you, just go with it."

But I'd also like to add, attenuators, such as the THDs are relatively inexpensive no?

They also do not alter the amp in anyway, no modifications.

& they're portable, you can use one with any number of amps.

[KevinOConnor]

Hi Guys

Well, one of our Power Scale kit customers told us that the kit and installation cost him about half the price of a Hotplate.

So, there is "inexpensive" and "even more inexpensive".

The proof is in the listening.

Have fun
Kevin O'Connor

[okgb]

I posted in another thread and can't see it now , but
to be clear i was asking if the newer marshall are
your circuit or some other variation .

As mentioned i like concept of your's But
like invasive surgery , I don't think i'd consider it for my '73 marshall 50 w
but for a scratch build where you can plan it in , why not
It was a few hundred dollars though , right ?

[Beck-Ola]

I guess nobody has had power scaling installed in a Vintage Modern yet? Apparently it would cost somewhat less for a 50 watter than a 100 watter because of the lower B+ voltage in the 2266. Look forward to somebody reporting in that they've had one installed. Seems like something worth doing if a guy plans to hang onto their VM for the long term and especially if using HDR a lot.